1. Field of the Invention
The present invention relates to a liquid suction apparatus for sucking a liquid from a plurality of nozzle openings of a liquid ejecting head and a liquid ejecting apparatus having this liquid suction apparatus.
2. Description of the Related Art
As a typical example of a conventional liquid ejecting apparatus, there is an ink jet printer having an ink jet printing head for image recording. As other liquid ejecting apparatuses, for example, an apparatus having a color material jet head used for manufacturing a color filter of a liquid crystal display, an apparatus having an electrode material (conductive paste) jet head used for forming electrodes of an organic EL display or an FED (Face Emission Display), an apparatus having a biological organic substance jet head used for manufacturing biological chips, and an apparatus having a sample jet head as a precise pipette may be cited.
An ink jet printer as a typical example of a liquid jet recorder makes comparatively small noise during printing and moreover can form small dots in high density, so that it has been used recently in various types of printing including color printing.
Such an ink jet printer generally has a printing head (liquid ejecting head) which is loaded on a carriage and moves back and forth in the width direction (head scanning direction) of a recording medium such as recording paper and a feed means for moving the recording medium in the direction (medium feed direction) perpendicular to the head scanning direction.
In the ink jet printer, printing is executed by ejecting ink drops (liquid drops) from the printing head to the recording medium in correspondence with print data. And, the printing head loaded on the carriage is structured so as to eject various colors of ink, for example, black, yellow, cyan, and magenta, thus not only text printing by black ink but also full color printing can be executed by changing the ejection rate of each ink.
Since the aforementioned printing head prints by ejecting ink pressurized in a pressure chamber as ink drops from the nozzle opening toward the recording medium, a problem arises that for example, by increasing of the ink viscosity caused by evaporation of a solvent from the nozzle opening, setting of ink, attachment of dust, moreover inclusion of air bubbles, defective printing is caused.
Therefore, when the nozzle opening of the printing head is clogged or when an ink cartridge is exchanged, the nozzle opening forming face of the printing head is sealed by the cap member, and ink is sucked and ejected from the nozzle opening by negative pressure from a suction pump (tube pump), thus a liquid suction apparatus for executing a cleaning operation for preventing defective ink ejection due to clogging by ink setting in the nozzle opening or inclusion of air bubbles into the ink feed path is generally included in the ink jet printer.
A conventional liquid suction apparatus, for example, described in Japanese Patent Laid-Open Publication No. 2001-096758, has a suction pump and a cap member connected to the suction pump for sealing a nozzle forming face of a printing head. And, in the conventional liquid suction apparatus, in a state that the nozzle forming face is sealed by the cap member, a liquid (air, ink) is ejected from the inside of the cap member by the suction pump. By doing this, due to a negative pressure generated inside the cap member, ink in the printing head and on the upstream side thereof is sucked and the printing head is internally cleaned.
By this cleaning operation (ink suction operation), filling the printing head with ink, suction and ejection of deteriorated ink from the printing head, and ejection of air bubbles generated in the ink in the printing head are carried out, and the ink filling state in the printing head is kept normal, and good printing is made possible.
Further, the suction pump is operated by an instruction from the controller in the printer or the host computer, thus the negative pressure generation time and negative pressure generation amount can be controlled.
FIG. 18 shows a state that the nozzle forming face of the printing head of the conventional ink jet printer is sealed by the cap member and a cap member 60 is in contact with a nozzle forming face 23 of a printing head 9 in which a plurality of nozzle openings 22 are formed. Inside the cap member 60, a filter member 62 is arranged in close contact with the bottom of the cap member 60. A liquid (air, ink) in the cap member 60 is sucked and ejected by a pump 61.
In the conventional ink jet printer shown in FIG. 18, not only in a case of execution of cleaning but also in a case that the ink jet printer is in a non-printing state, the nozzle forming face 23 of the printing head 9 is sealed by the cap member 60. The filter member 62 installed in the cap member 60 is in a wet state due to ink ejected from the printing head 9 at the time of cleaning or flashing. Therefore, when the nozzle forming face 23 of the printing head 9 is sealed by the cap member 60, the humidity in the cap member 60 is increased, and the moisture retention effect in the neighborhood of the nozzle openings 22 is increased, thus the setting of ink in the nozzle openings 22 can be suppressed.
In the conventional liquid suction apparatus aforementioned, as shown in FIG. 18, the filter member 62 is arranged in close contact with the inner bottom of the cap member 60. Therefore, in the entire filter member 62, in the neighborhood of an ejection port 63 formed in the bottom of the cap member 60, comparatively high suction force is reserved for a liquid (air, ink), while in the area away from the ejection port 63, no sufficient suction force can be obtained. Namely, the suction force for ink flowing down on the top of the filter member 62 differs depending on the position in the entire filter member 62 and ink concentratedly passes through the part in the neighborhood of the ejection port 63. In this case, the filter function of the entire filter member 62 cannot be used effectively, and the filter member 62 is locally deteriorated rapidly in the neighborhood of the ejection port 63 as well, thus a problem arises that the life span of the filter member 62 is shortened.
Furthermore, in the conventional liquid suction apparatus, after ending of filling of ink after exchanging the ink cartridge or even after the nozzle opening is recovered from clogging, as long as the negative pressure generating unit is operated, the ink suction flow rate is not suppressed and ink is continuously sucked from the nozzle opening.
In cleaning of a printing head having a plurality of nozzle openings, particularly a plurality of nozzle openings for different ink kinds, due to the structure of ink flow path or the composition factor of ink, the negative pressure and ink suction rate necessary for cleaning may be different for each nozzle opening or nozzle opening group. Therefore, in the conventional liquid suction apparatus, there is a problem imposed that depending on the difference in the required time for recovery of clogging or filling of ink for each nozzle opening or each nozzle opening group, an amount of ink larger than necessary is sucked for the easily recoverable nozzle opening or nozzle opening group and although there is a non-recovered or non-filled nozzle, the suction operation is ended at the point of time when the total suction amount reaches a set value. Further, there is another problem imposed that due to ink suction from a nozzle opening recovered from clogging, the negative pressure in the cap member is reduced, thus the effective transfer of negative pressure to a nozzle opening which is not recovered from clogging yet is prevented.
Further, the operation of the negative pressure generating unit is controlled on the basis of information such as the continuous non-printing time of the printer. However, the ink clogging state is affected by various factors including the temperature and humidity history, so that it is difficult to adjust the operation of the negative pressure generating unit in accordance with such an actual condition and suck ink in proper quantities in correspondence to various ink clogging states of the printing head. Therefore, a case that an unnecessarily large amount of ink is sucked during the cleaning operation and the ink consumption efficiency is adversely affected is caused.
The present invention has been developed with the foregoing in view and is intended to provide a liquid suction apparatus for a liquid ejecting head capable of sufficiently using a filter function of a filter member installed in a cap member overall the filter member body and a liquid ejecting apparatus having the liquid suction apparatus.
Further, the present invention is intended to provide, even when liquid suction conditions necessary for recovery of clogging or filling of ink are different for each nozzle opening or nozzle opening group, a liquid suction apparatus for a liquid ejecting head capable of suppressing excessive liquid suction from a nozzle opening or a nozzle opening group of easy recovery of clogging or easy filling of ink and efficiently applying negative pressure to a non-recovered or non-filled nozzle opening or nozzle opening group and a liquid ejecting apparatus having the liquid suction apparatus.
Further, the present invention is intended to provide a liquid suction apparatus for a liquid ejecting head capable of suppressing suction of an unnecessarily large amount of liquid during the liquid suction operation and a liquid ejecting apparatus having the liquid suction apparatus.
To solve the aforementioned problems, the present invention is a liquid suction apparatus for sucking a liquid from a plurality of nozzle openings of a liquid ejecting head for ejecting liquid drops toward an object from said plurality of nozzle openings, comprises: a cap member configured to internally form a closed space when said cap member makes contact with a nozzle forming face of said liquid ejecting head; a negative pressure generating unit configured to eject a fluid in said closed space formed in said cap member and generate negative pressure in said closed space; and a filter member arranged so that at least a part thereof is positioned in said cap member, wherein a common negative pressure chamber is formed on a downstream side of said filter member in a liquid flow direction during suction, said common negative pressure chamber being configured to apply an almost uniform negative pressure on almost overall said filter member, said negative pressure generating unit being connected to said cap member so as to eject a fluid in said common negative pressure chamber.
Preferably, said filter member is structured so that when said cap member makes contact with said nozzle forming face, a liquid receiving space is formed between said nozzle forming face and said filter member.
Preferably, said liquid receiving space is a single space corresponding to all of said plurality of nozzle openings.
Preferably, said liquid receiving space is divided into a plurality of individual spaces.
Preferably, said plurality of nozzle openings constitute several nozzle rows, said plurality of individual spaces being formed in correspondence with respective several nozzle rows.
Preferably, said filter member is structured so as to effectively function only in narrow areas extending along positions opposite to said respective several nozzle rows.
Preferably, said plurality of individual spaces are formed for each nozzle opening group composed of a plurality of nozzle openings of a common liquid kind to be ejected.
Preferably, said plurality of individual spaces are formed by partition members provided separately from said filter member.
Preferably, said plurality of individual spaces are formed by said filter member itself.
Preferably, said filter member is structured so as to make close contact with at least a part of said nozzle forming face when said cap member makes contact with said nozzle forming face.
Preferably, said filter member is structured so as to make close contact with almost overall said nozzle forming face when said cap member makes contact with said nozzle forming face.
Preferably, said filter member is structured so that a part thereof is projected from said cap member toward said nozzle forming face.
Preferably, said common negative pressure chamber is filled with a fluid permeable filler material, said fluid permeable filler material having a fluid resistance such that substantially uniform pressure is generated in overall said common negative pressure chamber when a gas passes through said common negative pressure chamber.
Preferably, said filler material is an expanding agent.
To solve the aforementioned problems, the present invention is a liquid suction apparatus for sucking a liquid from a plurality of nozzle openings of a liquid ejecting head for ejecting liquid drops toward an object from said plurality of nozzle openings, comprises: a cap member configured to internally form a closed space when said cap member makes contact with a nozzle forming face of said liquid ejecting head; a negative pressure generating unit configured to eject a fluid in said closed space formed in said cap member and generate negative pressure in said closed space, said negative pressure generating unit including a suction pump and a suction pipe connecting said suction pump to said cap member; and a flow rate control unit installed in a middle of said suction pipe, said flow rate control unit being configured to control a flow rate of liquid by a liquid flow resistance.
To solve the aforementioned problems, the present invention is a liquid ejecting apparatus comprises: a liquid ejecting head configured to change pressure of a liquid in pressure chambers respectively interconnecting to a plurality of nozzle openings and eject liquid drops toward an object from said nozzle openings; and any one of aforementioned liquid suction apparatuses.
According to the present invention having the aforementioned constitution, the common negative pressure chamber configured to apply almost uniform negative pressure on almost entire rear of the filter member is installed, so that the filter function of the filter member installed on the cap member can be used sufficiently overall the filter member.
Further, according to the present invention, even when liquid suction conditions necessary for recovery of clogging or filling of a liquid are different for each nozzle opening or a nozzle opening group, excessive liquid suction from a nozzle opening or a nozzle opening group of easy recovery of clogging or easy filling of a liquid can be suppressed and negative pressure can be effectively applied on a non-recovered or non-filled nozzle opening or nozzle opening group.
Further, according to the present invention, when the liquid suction operation for sucking a liquid from a plurality of nozzle openings of the liquid ejecting head is to be performed, suction of an unnecessarily large amount of liquid can be suppressed.